Sunday, November 09, 2014

Which Right Fielders Made The Best And Worst PIZAA in 2014?

Most of the readers of this blog are aware of the advanced fielding statistics at sites like FanGraphs and Baseball-Reference. A metric such as Defensive Runs Saved (DRS) gives us an idea of a player’s overall fielding performance. It is given as runs saved above what would be expected from the average player at the given position. It is discussed in more detail in the fielding glossary.

You may also have noticed two additional columns at FanGraphs labeled RZR and OOZ. These are the Revised Zone Rating statistics developed by John Dewan, president of Baseball Info Solutions. Dewan later developed the more detailed DRS metric. The Revised Zone Rating system is comprised of the following measures:

Balls in play within a fielder’s zone (BIZ)

Plays made in the zone (Plays)

Proportion of balls in zone converted into outs (RZR)

Plays made outside the zone (OOZ)

A play is considered to be inside a positional zone if half the balls hit into that area are converted into outs by all the players in baseball at that position. While the Revised Zone Rating system is less sophisticated than DRS, it is useful because it separates the plays a player made inside his zone from the plays outside his zone. Unlike DRS, the Revised Zone Rating system includes all shift plays and is thus is not easily interpreted for infielders. It is more useful for evaluating outfield defense which is less influenced by shifts.

Table 1 below shows how the distinction between in-zone and out-of-zone plays can be useful. Mets right fielder Curtis Granderson converted 180 out of 207 (87.0%) of balls in his zone into outs in 2014. Nationals right fielder Jayson Werth had a similar number of balls hit into his zone (204) but had a higher RZR (93.1%). Conversely, Werth made fewer out-of-zone plays (58) than Grandrson (85). These data suggest that Werth may have been the steadier fielder on balls hit in the right field zone but that Granderson was better at making difficult plays.

Some readers may have wondered whether these statistics could be translated to runs above average like most of the other defensive metrics. A few years ago, Colin Wyers (who has since been hired by the Houston Astros) developed an algorithmwhich combined RZR and OOZ and translated these numbers into plays made above average (PMAA) and runs saved above average (RSAA). Wyers' algorithm has a lot of steps and I'm not going to repeat the whole process here. If you want see all the math, you can read my post from two years ago.

Table 2 below shows the MLB leaders among right fielders in 2014. The top right fielder in the majors was Jason Heyward of the Braves with 44 PMAA. The 44 plays made can be broken down into two parts: 4 Plays in Zone Above Average (PIZAA) and 40 Plays Out of Zone Above Average (OOZAA). PIZAA and OOZAA may be two of the most amusing acronyms out there and you are probably relieved that I didn't show all the math. Simply stated though, Heyward was little above average on plays in the right field zone and exceptional outside the zone.

The final column of the table shows that Heyward saved an estimated 37 runs for the Braves. Heyward was also rated as spectacular by DRS (+32),Baseball-Reference's Total Zone (+30) and Baseball Prospectus' FRAA (+27).

The worst right fielder according to this metric was Torii Hunter who cost the Tigers an estimated 19 runs with his defense. Thus, the Tigers theoretically could have gained two wins if Hunter had been just an average right fielder. Hunter had -3 PIZAA and -20 OOZA which shows that he was particularly bad on plays made outside the right field zone. These data are further evidence that Hunter's poor fielding offset most of the offensive production that he provided.

There wasn't really an obvious gold glove in right field in the AL. Most of the ones with good statistics didn't have a lot of playing time. Still, Markakis was an odd choice. Kevin Kiermaier, Josh Reddick and Daniel Nava finished ahead of him in the Fielding Bible voting.